diff --git a/scripts/cloudron-setup b/scripts/cloudron-setup
index 3cca1c626..a821b1ebc 100755
--- a/scripts/cloudron-setup
+++ b/scripts/cloudron-setup
@@ -99,6 +99,11 @@ if [[ "${ubuntu_version}" != "16.04" && "${ubuntu_version}" != "18.04" && "${ubu
     exit 1
 fi
 
+if which nginx >/dev/null || which docker >/dev/null || which node > /dev/null; then
+    echo "Error: Some packages like nginx/docker/nodejs are already installed. Cloudron requires specific versions of these packages and will install them as part of it's installation. Please start with a fresh Ubuntu install and run this script again." > /dev/stderr
+    exit 1
+fi
+
 # Install MOTD file for stack script style installations. this is removed by the trap exit handler. Heredoc quotes prevents parameter expansion
 cat > /etc/update-motd.d/91-cloudron-install-in-progress <<'EOF'
 #!/bin/bash